Json4s: Trouble while trying to convert Json attribute to java.sql.Date

Question

I am using Json4s to deserialize json messages. I have a case class like

case class A(id: Int, b: Option[java.sql.Date])

Whenever I try to convert a json message to case class A, I get none as the value of b

scala> read[A]("""{"id":1,"b":12345}""")
res2: A = A(1,None)

scala> read[A]("""{"id":1,"b":"12345"}""")
res3: A = A(1,None)

scala> read[A]("""{"id":1,"b":"12/12/2014"}""")
res4: A = A(1,None)

How can I fix this issue

(`java.sql.Date` might not be supported though see: https://github.com/json4s/json4s/blob/master/ext/src/main/scala/org/json4s/ext/JodaTimeSerializers.scala) — Gábor Bakos, Nov 23 '14 at 09:02
Yeah, you are right. Any idea how to write a custom serializer :) — mohit, Nov 23 '14 at 09:07

score 3 · Accepted Answer · answered Nov 23 '14 at 09:26

Something along these lines (you might want to be more specific with formats). And then mix this trait in the classes which need to have access to this custom serializer.

import org.json4s.DefaultJsonFormats._

trait JsonFormats {

  case object DateSerializer extends CustomSerializer[java.sql.Date](format => (
    {
      case JString(s) => Date.valueOf(s)
      case JNull => null
    },
    {
      case d: Date => JString(d.toString())
    }
    )
  )

  implicit val json4sFormats =  native.Serialization.formats(NoTypeHints) + DateSerializer    
}

Json4s: Trouble while trying to convert Json attribute to java.sql.Date

1 Answers1